Interfacial roughness scaling and strain in lattice mismatched Si0.4Ge0.6 thin films on Si

Abstract

Interfacial roughness parameters and lattice strain of Si0.4Ge0.6 films with varying thickness epitaxially grown on Si(100) were determined using the techniques of grazing-incidence x-ray scattering and diffraction. The roughness of both the buried interface and sample surface follows a similar power-law scaling behavior with an exponent β around 0.71 for films below the critical thickness, and it undergoes a large change above the critical thickness. Observation of such a scaling law thus establishes a quantitative correlation between the interfacial roughness and lattice strain, and also allows the prediction of interfacial roughness as a function of film thickness of this compound.